GB725656A - Improvements in or relating to method of forming glass shapes and the resulting product - Google Patents

Abstract

725,656. Glass manufacture. THOMPSON CO., H. I. Jan. 14, 1953 [Jan. 29, 1952], No. 1096/53. Class 56. Articles are made from high melting-point glasses, i.e. above 1650‹C. by mixing the glassforming materials in powdered form with a binder, moulding the powder to the required shape, heating it to the fusing point, and cooling. Suitable binders are dilute sodium silicate and potassium silicate solutions, clay or Portland cement, the water content being adjusted to give a good cohesive and extrusive mass, water, plastics, either of thermoplastic or thermosetting type, chlorinated rubber or the silicone resins. If the binder is such that it will lose its binding properties before the fusing temperature is reached, incipient fluxes are added to the mixture, which fluxes fuse and bind the particles of glass-making materials together until they are themselves fused. Examples of fluxes are sodium meta borate, sodium tetra borate, boric acid, boron sesquioxide, sodium carbonate, potassium carbonate, lithium carbonate, sodium nitrate, potassium nitrate, sodium and potassium phosphates and equimolar mixtures of potassium and lithium fluoride. As described, the powdered mass is shaped by extrusion and the glass rod so formed is immediately drawn into fibre form. The extruder 1 delivers the extruded rod 11 into the chamber 6 of a furnace 4 heated by burners 5, 9. In the upper part of the furnace, the rod 11 is dried and cured. In the neck 8, the temperature is such that the incipient fluxes are fused. The burners 9 increase the temperature to and beyond fusion point of the glass, so that the fibre is drawn by a rotating reel 15 or by a transverse blast which blows the fibre through the bottom of a side wall of the furnace, on to a conveyer travelling Upwardly at the point of reception. The fibres are held on the vertical flight of the conveyer by a vacuum box. The fibre is collected on the conveyer in batt form and is removed from a horizontal run of the conveyer by a scraper. The burners 9 may be directed axially of the rod 11 to avoid disrupting it by blast action. Direct contact of the burner gases with the rod 11 may be avoided by passing the rod through a muffle. Many glass compositions and fuel gas compositions are mentioned.